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linux/drivers/clocksource/dummy_timer.c

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clocksource: Add generic dummy timer driver Several architectures have a dummy timer driver tightly coupled with their broadcast code to support machines without cpu-local timers (or where there is a lack of driver support). Since 12ad100046: "clockevents: Add generic timer broadcast function" it's been possible to write broadcast-capable timer drivers decoupled from the broadcast mechanism. We can use this functionality to implement a generic dummy timer driver that can be shared by all architectures with generic tick broadcast (ARCH_HAS_TICK_BROADCAST). This patch implements a generic dummy timer using this facility. [sboyd: Make percpu data static, use __this_cpu_ptr(), move to early_initcall to properly register on each CPU, only register if more than one CPU possible] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com>, Cc: John Stultz <john.stultz@linaro.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1370291642-13259-3-git-send-email-sboyd@codeaurora.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-06-04 04:33:53 +08:00
/*
* linux/drivers/clocksource/dummy_timer.c
*
* Copyright (C) 2013 ARM Ltd.
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/clockchips.h>
#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/percpu.h>
#include <linux/cpumask.h>
static DEFINE_PER_CPU(struct clock_event_device, dummy_timer_evt);
clocksource/dummy_timer: Convert to hotplug state machine Install the callbacks via the state machine and let the core invoke the callbacks on the already online CPUs. Signed-off-by: Richard Cochran <rcochran@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153336.130385842@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-14 01:16:41 +08:00
static int dummy_timer_starting_cpu(unsigned int cpu)
clocksource: Add generic dummy timer driver Several architectures have a dummy timer driver tightly coupled with their broadcast code to support machines without cpu-local timers (or where there is a lack of driver support). Since 12ad100046: "clockevents: Add generic timer broadcast function" it's been possible to write broadcast-capable timer drivers decoupled from the broadcast mechanism. We can use this functionality to implement a generic dummy timer driver that can be shared by all architectures with generic tick broadcast (ARCH_HAS_TICK_BROADCAST). This patch implements a generic dummy timer using this facility. [sboyd: Make percpu data static, use __this_cpu_ptr(), move to early_initcall to properly register on each CPU, only register if more than one CPU possible] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com>, Cc: John Stultz <john.stultz@linaro.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1370291642-13259-3-git-send-email-sboyd@codeaurora.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-06-04 04:33:53 +08:00
{
clocksource/dummy_timer: Convert to hotplug state machine Install the callbacks via the state machine and let the core invoke the callbacks on the already online CPUs. Signed-off-by: Richard Cochran <rcochran@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153336.130385842@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-14 01:16:41 +08:00
struct clock_event_device *evt = per_cpu_ptr(&dummy_timer_evt, cpu);
clocksource: Add generic dummy timer driver Several architectures have a dummy timer driver tightly coupled with their broadcast code to support machines without cpu-local timers (or where there is a lack of driver support). Since 12ad100046: "clockevents: Add generic timer broadcast function" it's been possible to write broadcast-capable timer drivers decoupled from the broadcast mechanism. We can use this functionality to implement a generic dummy timer driver that can be shared by all architectures with generic tick broadcast (ARCH_HAS_TICK_BROADCAST). This patch implements a generic dummy timer using this facility. [sboyd: Make percpu data static, use __this_cpu_ptr(), move to early_initcall to properly register on each CPU, only register if more than one CPU possible] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com>, Cc: John Stultz <john.stultz@linaro.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1370291642-13259-3-git-send-email-sboyd@codeaurora.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-06-04 04:33:53 +08:00
evt->name = "dummy_timer";
evt->features = CLOCK_EVT_FEAT_PERIODIC |
CLOCK_EVT_FEAT_ONESHOT |
CLOCK_EVT_FEAT_DUMMY;
evt->rating = 100;
evt->cpumask = cpumask_of(cpu);
clockevents_register_device(evt);
clocksource/dummy_timer: Convert to hotplug state machine Install the callbacks via the state machine and let the core invoke the callbacks on the already online CPUs. Signed-off-by: Richard Cochran <rcochran@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153336.130385842@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-14 01:16:41 +08:00
return 0;
clocksource: Add generic dummy timer driver Several architectures have a dummy timer driver tightly coupled with their broadcast code to support machines without cpu-local timers (or where there is a lack of driver support). Since 12ad100046: "clockevents: Add generic timer broadcast function" it's been possible to write broadcast-capable timer drivers decoupled from the broadcast mechanism. We can use this functionality to implement a generic dummy timer driver that can be shared by all architectures with generic tick broadcast (ARCH_HAS_TICK_BROADCAST). This patch implements a generic dummy timer using this facility. [sboyd: Make percpu data static, use __this_cpu_ptr(), move to early_initcall to properly register on each CPU, only register if more than one CPU possible] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com>, Cc: John Stultz <john.stultz@linaro.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1370291642-13259-3-git-send-email-sboyd@codeaurora.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-06-04 04:33:53 +08:00
}
static int __init dummy_timer_register(void)
{
clocksource/dummy_timer: Convert to hotplug state machine Install the callbacks via the state machine and let the core invoke the callbacks on the already online CPUs. Signed-off-by: Richard Cochran <rcochran@linutronix.de> Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de> Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: rt@linutronix.de Link: http://lkml.kernel.org/r/20160713153336.130385842@linutronix.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-07-14 01:16:41 +08:00
return cpuhp_setup_state(CPUHP_AP_DUMMY_TIMER_STARTING,
"AP_DUMMY_TIMER_STARTING",
dummy_timer_starting_cpu, NULL);
clocksource: Add generic dummy timer driver Several architectures have a dummy timer driver tightly coupled with their broadcast code to support machines without cpu-local timers (or where there is a lack of driver support). Since 12ad100046: "clockevents: Add generic timer broadcast function" it's been possible to write broadcast-capable timer drivers decoupled from the broadcast mechanism. We can use this functionality to implement a generic dummy timer driver that can be shared by all architectures with generic tick broadcast (ARCH_HAS_TICK_BROADCAST). This patch implements a generic dummy timer using this facility. [sboyd: Make percpu data static, use __this_cpu_ptr(), move to early_initcall to properly register on each CPU, only register if more than one CPU possible] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Acked-by: Marc Zyngier <marc.zyngier@arm.com>, Cc: John Stultz <john.stultz@linaro.org> Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: linux-arm-kernel@lists.infradead.org Link: http://lkml.kernel.org/r/1370291642-13259-3-git-send-email-sboyd@codeaurora.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2013-06-04 04:33:53 +08:00
}
early_initcall(dummy_timer_register);
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